London, England (CNN) -- If you believe the mood music, the Tea Party's rise may mark a political watershed in the U.S.

The conservative grassroots movement, which has capitalized on right-wing frustration with Barack Obama's administration and the political establishment, is already shaping the agenda of American politics.

Tuesday's midterm elections could herald its arrival on Capitol Hill with Tea Party candidates such Rand Paul, Sharron Angle and Christine O'Donnell, having beaten more moderate Republicans in earlier primaries, all seeking election to the Senate.

But while the Tea Party's fiscal and social conservatism has chimed a populist chord with a growing army of American supporters, its popularity risks being hijacked by far-right groups in Europe with a more extremist agenda.

At a rally outside the Israeli Embassy in London on October 24, supporters of the English Defence League march through the streets waving union flags and the red and white cross of St. George, chanting: "I'm England 'til I die!"

The hardline group pushes an anti-Islamic message with provocative marches through neighborhoods with large Muslim populations. It has cultivated links with European far-right groups with a similar agenda, such as controversial Dutch lawmaker Geert Wilders' anti-Muslim Party for Freedom.

English Defence League leader Stephen Lennon is open about the nascent links between the group and a handful of Tea Party activists in the U.S.

"Individuals from their movement have contacted individuals from our movement supporting what we're doing, in the same way members from our group are supporting what they're doing," Lennon told CNN.

Lennon said EDL and Tea Party activists shared the common goal of fighting for freedom.

"Freedom is worth fighting for. And you'll see people fight back for freedom," he said. "That's what you're seeing in the U.S., you're seeing in Britain, you're seeing in Europe; the more Islam we have the less freedom we have, we're opposed to it."

Tea Party activist Rabbi Nachum Shifren, a surfing, hard-line Jewish politician from California who preaches a message of fear about Islamic extremism, is one of those who has embraced the EDL. Addressing the rally in London, Shifren said the group had "started the liberation of England."

Shifren told CNN that a lot of people in the Tea Party movement were concerned by radical Islam, and said he had established some "outrageously beautiful relationships" with EDL members.

"We are absolutely on the same page," said Shifren. "The EDL members tell me that they feel completely disenfranchised and out of the picture when it comes to their own government and I totally agree with them."

But Board of Deputies of British Jews Chief Executive Jon Benjamin said Shifren was displaying "breathtaking naivete and ignorance" by associating himself with the EDL. He said the EDL was attempting to play minorities off against each other.

"Regrettably, this result will only embolden extremists at the other end of the spectrum, and particularly the insidious EDL, who want nothing more than to sow fear and mistrust in the hope of attracting greater support," said Benjamin.

In the U.S., mainstream Tea Party activists deny they want links to extremists, either at home or abroad.

Adam Brandon of the conservative pressure group FreedomWorks told CNN the Tea Party was a "very peaceful non-violent movement" with no desire to court support among more extremist groups.

"Don't let anyone who is angry, anyone who is violent, even come close to your movement because they will end up defining it," Brandon said.

Those concerns are echoed by supporters of the British Tea Party, a loose alliance inspired by the success of the American movement which favors "lower taxes, less state interference, smaller government" -- an agenda inspired by the grievances behind the original Boston Tea Party in 1773 which triggered the American rebellion against British colonial rule.

Acknowledging that heritage, British Tea Party supporters launched their campaign earlier this year by tipping tea off a bridge in Boston, Lincolnshire, in eastern England.

Simon Richards of the campaign group Freedom Association, said British Tea Party supporters had not desire to court the support of extremists and were "maybe a little more libertarian" than their American counterparts.

"It is a matter of grave concern because we've seen how the American Tea Party movement has been damaged by some small numbers of extremists and we're very concerned that might happen here," Richards told CNN.

Daniel Hannan, a Conservative Party lawmaker in the European Parliament and British Tea Party supporter, also said it was wrong to suggest there was any place for far-right extremists in Tea Party politics on either side of the Atlantic.

"I don't think there is anything far-right about wanting lower taxes," Hannan told CNN. "Americans are no more anti-tax, than Brazilians, or British, or Pakistanis or anybody else; nobody likes giving money to the government.

"Of course, there are going to be some nasty people in any large movement -- that's inevitable when you have a mass organization -- but the essential idea that the government should live within its means is a remarkably moderate one."